Ask Dr. Rex

Posted by Mattias in Tutorials

“No, I don’t use loops. I create my own music.”

Discovering Reason 1 1

Heard it before? In all likelihood, yes. Oddly enough, the use of loops still remains a somewhat controversial issue. It’s in the twilight zone, that fuzzy grey area between artistry and “pushing a button”. After all, a loop is the product of someone else’s efforts, talent and creativity. But then again, isn’t that true for any kind of art? Aren’t you using sampled instruments that have been recorded – and played – by someone else? And synth presets that someone else programmed? Who do you owe credit to when you play a violin trill on the NN-XT – the guy who sampled it? The conductor? The violinist? Antonius Stradivarius, who built it? The truth is, at the hands of a skilled artist a bunch of raw loops can be molded into a unique piece of artwork that holds its own against any other musical accomplishment. And never was there a tool more powerful for tweaking, bending, carving and re-shaping loops than Dr.REX!

In this opening chapter of Discovering Reason we will explore this versatile device. We’ll start off with the simpler and more common applications, and as the article progresses we dig deeper until we reach the very bottom of Dr.REX’s bag of tricks!

Dr.REX – the Subtle Sizzler

Using a drum loop upfront as the main rhythm body is not necessarily the way to go. In fact, one could say – arguably – it’s unfashionable. In the late 1980s and early 90s sampled loops were all the rave, and excerpts from James Brown’s “Funky Drummer” (featuring Clyde Stubblefield) were all over the place. But since then, more subtle and sophisticated ways of using drum loops have evolved and if you were to ask anyone in the know how they approach drum loops they would probably answer something along the lines of “as icing on the cake”. The common approach is to program the drums on a drum machine or play them on a keyboard, and then use various sampled loops to spice up the main drums. Thanks to Dr.REX, this method is a no-brainer in Reason. Try this:

  1. Create the “main meat” of the drums using single samples in ReDrum or any of the samplers (NN-XT, NN19).
  2. Create a Dr. REX and find a drum loop that complements your programmed drums in terms of rhythm, feel etc, particularly in the higher frequency range.
  3. Use the filter on the Dr.REX – set it to HP mode (high pass) and use the FREQ slider to find a good spot for driving a wedge between the wanted and the unwanted frequencies.
  4. Insert a compressor with fairly aggressive settings (i.e. Ratio 4-8:1, Threshold 0, Release 0) to bring the subtle parts of the loop to the surface.

We have prepared a couple of examples of the above Dr.REX application (use track or mixer muting for quick comparison): hipass_sizzle1.rns | hipass_sizzle2.rns

Dr.REX – the Swing Supplier

Even if you don’t want to use a loop for its sound, you can still find the rhythmic feel of the loop appealing. Let’s say you find a certain conga loop that – even though you happen to loathe congas – has a nice groove to it that makes you wanna get up and do a funky little dance number. After all, it has this human feel to it that no stiffly programmed drum pattern can mimic. Well, go for it – just steal the groove and throw the congas on the fire! Here’s the procedure:

  1. Create a Dr.REX and open that groovy loop
  2. Click “To Track” on the Dr.REX
  3. In the sequencer window, right-click on the group you just created
  4. On the context-menu, select “Get User Groove”

Now the groove is all yours and you can find it on the Quantize grid drop-down menu as the last item: “User”. It remains there until the next time you do a “Get User Groove” and is saved with the song, ready to be applied to any riff or pattern you record.

Dr.REX – the Animation Animal

Another cool thing you can do, is to employ the Dr.REX as a rhythmic modulation source. Using CV/Gate, the groove of a REX loop can be applied to the timbre of a synth or sampler sound – adding life and pulse to even to the most static of textures. This doesn’t necessarily involve the Dr.REX as an actual sound source, it can just as well be kept silent – you only need it there to supply the groove, for “animation” purposes.

Here’s an example of a rather uninteresting sequence:

Now, by using a Dr.REX drum loop to control the filter of the synthesizer, the exact same sequence sounds like this:

(For setup reference, see animation1.rns or animation2.rns).

Dr.REX – the Shape Shifter

“Drums? What drums?” The fact that a loop features drums doesn’t dictate the way to use it. With the unique tweaking features of Dr.REX together with external modulation through CV/Gate, you can shape a drum loop – or any loop, for that matter – into something barely recognizable. Allow us to demonstrate: Here is a basic drum loop from the Factory Sound Bank:

Not much going on there, right? But with some elaborate use of filters, FX and Matrix sequencers we can take this loop and turn it into this:

Here’s a Reason Song version in case you want to see how it was done: abstracted.rns)

Dr.REX – the Melody Maker

At first glance it might seem a daunting task to shape a music loop into something useful: Wrong key, wrong chord progression, silly melody – how do I fit this into my song? So now we’re going to teach you how to gain ultimate musical control of the Dr.REX. First off, there are no less than six different ways to control the pitch of a REX loop:

  • Global Transpose (automation enabled)
  • Pitch of individual REX slices
  • Oscillator Pitch modulation by external source (CV)
  • Pitch Bend
  • LFO Pitch modulation
  • Envelope Pitch modulation

Using a combination of two or more of these will allow you to tame a music loop and have it follow you anywhere you want to go. Let’s begin shall we!

First, we open a simple bass loop called “Take Your Pick 01″ from the Reason Essentials ReFill package. In its original state, the loop sounds like this:

Then we “flatten” the loop by adjusting the pitch of some individual slices, to make the loop more manageable. With this particular bass sound that also means altering the timbre on a couple of notes since the entire fabric of tones and overtones is changed, but that only makes it more interesting. Here’s the result:

Dirty trick 1: And now for something completely different. We’re going to create an entirely new bass line by using a Matrix to control the pitch. This is a much more flexible method than tweaking the pitch of individual slices because it allows the pitch to be changed right in the middle of a single slice, and it also lets you play variations on the same Dr.REX without having to create multiple instances with different sequences. Users who like this approach would probably utilize the Curve grid on the Matrix to program the pitch sequence. But we’re not going to do that, we’ll reserve the Curve part for other things and instead use the Keys grid! But how? Note CV doesn’t correspond to pitch does it? Too right, it doesn’t. While it comes out as correct notes when connected to the Note CV input of any of Reason’s synths and samplers, the “voltage scale” doesn’t map onto a chromatic scale. The tiny difference in “virtual voltage” between a C and a C# doesn’t constitute a semitone increment if you connect Note CV out to Osc Pitch CV in. But through this little unorthodox trick, we’ll make it happen:

Osc Pitch

First, flip to the back side of the Dr.REX and connect Note CV on the Matrix to Modulation Input: Osc Pitch on the Dr.REX. Then, turn the knob next to the Osc Pitch input all the way to the right (value 127). This will “boost” the incoming CV so that it translates with 100% accuracy to semi-note values. Unfortunately, it will also thrust the pitch to near-supersonic range, so you will have to flip back to the front panel of the Dr.REX and turn the Osc Pitch: Octave knob all the way to the right (Value 0). Now you’re free to step program a new bass line in the Keys grid on the Matrix. Here’s an example of what that might sound like:

Neat! Now, just because a REX file contains a bass loop you don’t have to use it as a bass. Combining the tweaking possibilities of the Dr.REX you can turn it into a guitar, a staccato chord, whatever you want. Here’s an example of multiple Dr.REX, all playing the same old bass loop but in completely different ways:

Now let’s try that with drums on top:

Dirty trick 2: Right, so now that we’ve exhausted the Matrix-to-Pitch option and the pitch-per-slice option, is that it? Nope, there’s yet another layer in store. This trick is actually not ‘dirty’ at all, it’s documented in the Dr.REX specification, but far from all users are aware of it. You can transpose the Dr.REX from your MIDI keyboard using standard Note-on messages. This is by far the easiest and most “musician friendly” method of controlling of the pitch. All you need to do is to adjust the Octave range of your MIDI keyboard so that you can play the very bottom notes C-2 to C0.

Now let’s use that in combination with the earlier trick (Matrix controlled pitch) to first create a custom sequence and then trigger the overall pitch from the keyboard.

We start with a loop from the Synthotica refill called “80 manip”. This is a straightforward sequence playing the same note, and sounds like this:

Using “dirty trick #1″, we program a sequence on the Matrix that controls the Osc Pitch of the Dr.REX. We also add effects, have some with filters, and push the tempo. Result:

Last but not least, we record the “macrolevel transpose”: a simple 4-note (whole notes) sequence on the Dr.REX sequencer track. Voilá:

Instant techno! The only thing missing is some vulgar techno drums, so let’s get that over with:

Bottom line

As you can see, there’s more to Dr.REX and REX files than rigid loop playback. Dr.REX is arguably the most unique instrument in the Reason environment, and the real fun begins once you go beyond the drum loops and start exploring other possibilities – try slicing up a vocal, guitar, bass or hardware synth recording in ReCycle and see how far you can push it in Dr.REX with filters, modulation, quantizing, transposition, randomization – the Doctor is always on duty, just ask!

Text & Music by Fredrik Hägglund

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